Summary: PROOF COPY [BP10610] 133839PRB
PROOF
COPY
[BP10610]133839PRB
Simulation of nanodiamond and nanographite formation from molten carbon
in the presence of hydrogen
A. Sorkin, Joan Adler,* and R. Kalish
Department of Physics, Technion, Israel Institute of Technology, Haifa 32000, Israel
Received 11 February 2008
Hydrogen plays a significant role in the formation of nanodiamond, terminating diamond surfaces, and
removing sp2
-bonded atoms from the surface during chemical-vapor deposition diamond growth. However,
there are only few calculations that simulate nanodiamond development directly and even less that do so in a
hydrogen-containing environment. Recently, nanoscale graphitic layers embedded in amorphous carbon were
observed experimentally. We report here on results from a comprehensive study of nanodiamond and nan-
ographite formation from molten carbon in the presence of hydrogen under varied conditions of external
pressure and cooling rate. We find that hydrogen-free nanodiamond crystals are precipitated more readily at
increased melt densities and cooling rates, whereas slower cooling rates permit formation of graphitic layers.
DOI: XXXX PACS number s : 62.50. p, 81.05.Uw, 61.43.Bn
I. INTRODUCTION